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By © Charles P. Vick 2007 All Rights Reserved


JUMPSEAT - SIGINT Spacecraft Series – ( NRO/USAF/ NSA - Program AFP-711)

Code name JUMPSEAT was the next in a long series of earth orbit USAF/NSA, SIGINT (signals intelligence) spacecraft used by the USAF and intelligence Community for a variety of mission. They were launched by the Titan-23B Ascent Agena-D and later Titan-34B Ascent Agena-D boosters with a total of at least eight or more successful launches total identified. The spacecraft were actually nothing more than USAF mission specific sophisticated earth orbit space based earth receiving stations operating over the entire emitted electro magnetic radio spectrum frequency range. The JUMPSEAT spacecraft introduced the first unfurling dish structures “wrap-rib” large deployable gold mesh covered receiving dish antenna design of about 72 feet in diameter with a total spacecraft mass of about 1,500 pounds. JUMPSEAT’s first known launch was apparently March 21, 1971 and its subsequent launches were on February 16, 1972, August 21, 1973, March 10, 1975, February 25, 1978?, August 5, 1978, April 24, 1981, July 31, 1983 and its last launch was apparently on February 21, 1987. They were designed to monitor and pick up from the ground and in flight electronic signals intelligence (ELINT), radio, communications intelligence (COMINT) and radar emitters emissions intelligence (RADINT) in addition to the missile test flight telemetry intelligence (TELINT) acquisitions capabilities all coming under the general SIGINT heading. They were fully dedicated mission operations that were highly successful in acquiring SIGINT through the larger mission general SIGINT “wrap-rib” gold mesh covered reflector dishes.

The technology for these SIGINT spacecraft were slow in coming on line development wise but later proved out highly successfully once the technology was perfected. Like any new technology program it had its issues that slowed its initial progress. During the era they were developed it literally became a serious chase to just keep up with the developing foreign different kinds of monitor able electronic emitters emissions that these systems were able to monitor crying for larger more sophisticated systems able to do multiple missions at the same time.

Each gravity gradient stabilized spacecraft was about 72 feet in diameter with the dish attached to gimbals for steering from the command, communication, control and intelligence, power bus. JUMPSEAT’s dish did not cover the entire visible surface of the earth but covered more than its RHYOLITE predecessor and thus the dishes were presumable set on gimbals to monitor specific points or objects of interest such as ballistic missile flight test telemetry. This would thus require several spacecraft to accomplish this monitoring task over the full range of the ICBM’s flight test.

It is presumed that each spacecraft bus carried two solar arrays and perhaps two down link communications dish. The launch shroud was 10.0 feet in outside diameter with a total length of 40.03 feet. Under the fairing shroud nose cap was the part of the spacecraft which housed the sophisticated receiving feed horns with log periodic antennas collecting the earth based signals reflected off the large SIGINT dish.

Above the feed horn’s apparatus housing circumstantially there was a new adjunct ballistic missile early warning sensor payload Heritage/GEM sensor system deployed on the JUMPSEAT, SIGINT satellite new variation of which were later deployed on previous and subsequent USAF, SIGINT satellite. This was used by the satellite not merely to back up early warning capabilities but to help track ballistic missile flights in progress. This practice of using sophisticated infrared sensors on the USAF payload to help track foreign ballistic missile payloads continues to this day with dramatic success. Examples of this are the RADIANT AGATE / COBRA BRSSS system deployed on TRUMPET, SIGINT satellites would seem to indicate the early heritage of such adjunct payloads but there is no confirming USAF Space and Missile System Division histories on an otherwise silent highly classified adjunct payload deployment program. These examples are all USAF/NRO programs deployments only.

This spacecraft utilized the five foot diameter by 20.86 foot long Ascent Agena-D based stage to place it on a highly elliptical Molniya class orbit. They were operated at an inclination that was at approximately 62.5-63.5 degrees with a perigee of about 295 kilometers and an apogee of about 39,338 kilometers with a spacecraft life of five to seven years. This kind of orbit gives the satellites long linger time of the area’s of interest in order to acquire the data desired that might otherwise be lost. Each JUMPSEAT Agena-D is believed to have deployed at least one or up to two sub satellites SIGINT spacecraft.

The USAF/NSA primarily utilized it for monitoring Soviet missile test flights operations emissions. The Agena-D rocket stage portion of the SIGINT packages carried the usual assortment of earth, horizon and solar sensors to orient the spacecraft but it did not remain attached to the spacecraft. The constellation of spacecraft was able to receive and send the data to several global ground stations via radio signal operated by USAF/NSA personnel. The data was then processed and analyzed at NSA headquarters for further analysis distribution to the USAF intelligence community.


 1. McDowell, Jonathan , U. S. Reconnaissance Satellites Programs, Part 2: Beyond Imaging, Quest, Vol. 4, No. 4.

2. Klass, P, 1990 “NSA JUMPSEAT Program Winds Down…, Aviation Week & Space Technology, April 2, 1990 p. 46.

3. Dr Day, Dwayne A., Robotic Ravens, Spaceflight, Vol. 47, No. 11, Nov. 2005, pp. 426-433.

Conceptual USAF Jumpseat SIGINT Satellite Series

SIGINT Based Heritage IR Early Warning Sensor

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Page last modified: 21-07-2011 13:04:48 ZULU